The oaks will provide food in the form of acorns.... maybe in your lifetime /forums/images/graemlins/tongue.gif Just kidding. However, from what I've read, Oaks don't start producing acorns until they are at least 20 years old or older, depending on many factors like species, location, soil, climate, etc...
Oak Facts (depending who you believe /forums/images/graemlins/wink.gif)
How to manage oak forests for acorm production.
The flowering trees will yeild food for wildlife faster than the oaks, if that is what you are after, especially on the edges of an existing forest. We planted a forest about 15 years ago. Around 2150 trees. The trees were planted in alternating rows of pine and mixed hardwoods with a border of flowering trees and shrubs. The pines are averaging about 30ft tall and so are the mixed hardwoods. There are at least 7 species of oak in there and we have yet to see an acorn on any of them. Lots of pine cones, however. The flowering trees, on the other hand, have produced fruits for wildlife since the second year. There are crabapples, olives, spice bushes, dogwoods, cherries, etc...
If you want quick results for wildlife food, go with flowering trees and shrubs. If you want long term habitat, go with the oaks. By planting a forest, we got the best of both worlds.
Regardless of what you end up planting, plant something. Trees are great yardsticks to measure time. I get a great feeling walking in our forest. I remember the day they were planted like it was yesterday. Old cornfield on poorly producing sand. Light rain in the early spring making the scrubby grasses soak your legs as you walked through them. Didn't look like much when that day was over, but now you can't believe how thick and healthy that little forest is. Good luck in you planting. /forums/images/graemlins/smile.gif